Japanese Examined Utility Model Publication 62-8957 and Japanese Unexamined Patent Publication 60-30596 disclose a laser beam machining device of this type, which transports a workpiece to a working position where laser beam machining is carried out.
The workpiece transport device disclosed in Japanese Examined Utility Model Publication No. 62-8957 includes an intermediate conveyer, in which an upper transport passage and a lower transport passage are opposed to a laser beam machine. A transport-in conveyer is located at a first side of the intermediate conveyer. The transport-in conveyer vertically moves between positions corresponding to the upper transport passage and the lower transport passage. A transport-out conveyer is located at a second side of the intermediate conveyer. The transport-out conveyer vertically moves between positions corresponding to the upper transport passage and the lower transport passage.
When the transport-in and the transport-out conveyers are placed at a position corresponding to the upper transport passage, and when a pallet carrying a workpiece is placed on the transport-in conveyer, the pallet is transported into the upper passage of the intermediate conveyer from the transport-in conveyer. The workpiece is machined by means of the laser beam machine, and simultaneously, the pallet carrying the machined workpiece is transported onto the transport-out conveyer from the upper transport passage of the intermediate conveyer. Further, after the machined workpiece is removed from the pallet, the transport-in and transport-out conveyers are lowered to the position corresponding to the lower transport passage. With both conveyers in this position, the empty pallet is transported back to the transport-in conveyer from the transport-out conveyer via the lower transport passage of the intermediate conveyer.
A workpiece transport device disclosed in Japanese Unexamined Patent Publication No. 60-30596 includes a work station for the laser beam machine. A first setting station for attaching a workpiece on a pallet is provided at a first side thereof. A second setting station for removing the workpiece from the pallet is provided at a second side thereof. A conveyer for returning the pallet is provided between the first and second stations, detouring around the work station.
After a workpiece is mounted on the pallet at the first station, the pallet is transported to the work station from the first station. The workpiece is cut by the machine and, simultaneously, the pallet carrying the machined workpiece is transported to the second station from the work station. Further, at the second station, after the machined workpiece is removed from the pallet, the empty pallet is transported back to the first station from the second station by means of the conveyer that makes a detour around the work station.
These conventional devices have their first and second stations spaced at opposite sides of the work station. This arrangement precludes the possibility of attaching and removing a workpiece at a single station. Therefore, it is difficult to automate the workpiece attaching and removing operations in order to achieve unmanned operation.
Furthermore, in other conventional devices, each workpiece should be chucked before the workpiece is transported into the work station. In this situation, each workpiece is stamped by the laser beam at the machining position. A micro-joint method is used to prevent the stamped portions from falling. Therefore, the connecting portion of the workpiece treated by the micro-joint method should be broken off with a hammer. The broken-off portion of the workpiece must be ground for finishing. Thus, the process is extremely troublesome.